With steer-by-wire vehicle steering systems, there is no mechanical connection between a steering wheel and the steered vehicle wheels. Instead, the steering handle in such a vehicle steering system serves as an input device for a driver's steering command that is detected by suitable sensors. A desired steering angle of the steered vehicle wheels is adjusted by means of the steering command, possibly taking into account other vehicle parameters, and an adjusting apparatus actuating the vehicle wheels. Due to the lack of a mechanical connection, the driver does not experience any direct feedback from the vehicle wheels. Even with a steer-by-wire vehicle steering system, it is nonetheless desirable to communicate to the driver a steering sensation that basically corresponds to that of a conventional vehicle steering system with a mechanical coupling between the steering wheel and the vehicle wheels, i.e., when steering, the driver experiences a resistance from the steering wheel depending on the driving situation, and can return the steering wheel into its straight-ahead position.
A steering handle for a steer-by-wire vehicle steering system is known from DE 101 57 797 A1. On the one hand DE 101 57 797 A1 proposes actively providing the resistance by means of an electric motor and, on the other hand, additionally providing a passive apparatus that produces additional reaction torque to a steering command by the driver. By doing this, a main body of the steering handle is connected to a shaft for conjoint rotation that, for its part, is drivingly coupled to a rotor of an electric motor, wherein a planetary gear is arranged between the shaft and the electric motor to reduce the rotational speed of the electric motor. The planetary gear is arranged on the side of the electrical motor facing away from the main body. In a region between the main body and the electric motor, the rotatable shaft is provided with a thread on its outer circumference that engages with a ball screw nut. Given a rotary movement of the main body and hence the shaft, the ball screw nut is axially displaced against the force of return springs in order to produce opposing torque for manual torque applied to the main body by the driver. The passive device especially serves to further produce a resistance in the event of a failure of the electric motor in order to make it easier to handle the vehicle.